Pumps are commonly used in I.V. therapy for the administration of I.V. fluids to a patient. The use of pumps, however, can pose problems when it becomes necessary or desirable to move the patient. These problems are particularly apparent when the pumps are sophisticated, relatively cumbersome, and require extensive peripheral apparatus. Unlike the simple I.V. bottle administration set which allows a patient to move from one location to another with relative ease, when a pump is used for I.V. administration, the cumberous nature of the apparatus can effectively inhibit mobility of the patient.
The problem is aggravated by the fact that typical I.V. systems which use a piston type pump do not provide for disengagement of the fluid line from the pump to leave the fluid line patent between the source and the patient. Instead, such systems usually incorporate a valving device which either fills the pumping chamber or pumps fluid from the pumping chamber. In each of these configurations, the valve does not allow direct fluid flow from the fluid source to the patient. Several examples of this type of I.V. pump and associated disposable pump chamber cassettes are available. Specifically, U.S. Pat. No. 3,985,133 to Jenkins et al., U.S. Pat. No. 4,423,741 to Levy and U.S. Pat. No. 4,450,079 to Farr disclose pump chamber cassettes for I.V. pumping devices which do not contemplate a patent fluid line between the fluid source and the patient.
In order to improve the flexibility of an I.V. pump administration system, there is a recognized need for the capability to disconnect the fluid line from the pumping mechanism for periods of time without breaking into the fluid line or interrupting infusion. Furthermore, there is a need to maintain the integrity of the fluid line during disengagement from the pump to prevent the admission of air into the I.V. system and prevent bacterial contamination of fluids. Several situations can be envisioned where the ability to remove the fluid line from a pumping mechanism would be desirable. For example, there is always the potential need to move the patient unencumbered by the pumping mechanism itself. Further, there may be situations when it is necessary to administer fluid to a patient at a rate faster than is possible by the pumping system, such as would be the case with a burn victim where up to 3 liters of fluid per hour may be required. Also, there are instances when the pumping mechanism may become inoperative and it is desirable to continue the uninterrupted infusion of fluids to the patient during repair or replacement of the pump.
Several fluid flow valving mechanisms have been suggested in the prior art. Of these, some valving mechanisms have been suggested which permit the mixing of fluids from several sources or the redirection of fluid from one source to another. More specifically, fluid valves have been suggested which accomplish these functions by incorporating a slidable and rotatable cylinder in operative association with a housing having various fluid inlet and fluid outlet ports. For example, U.S. Pat. No. 3,269,412 to Badke and U.S. Pat. No. 4,423,741 to Levy disclose reciprocating piston valves having various fluid paths defined therein which are oriented with fluid inlets and outlets to define particular fluid paths through the device. These references, however, do not teach or suggest a cassette pump valve which is restrained to provide for normal valving during the pumping operation and which, upon disengagement of the cassette from the pump, can be repositioned within the cassette to provide for the gravity flow of fluid therethrough.
It is an object of the present invention to provide a means for disengaging an I.V. fluid line from a pumping means without interrupting the administration of fluids to the patient. It is another object of the present invention to allow for such disengagement without the admission of air into the fluid line and without contaminating the fluid being administered to the patient. It is yet another object of the present invention to provide a mechanism which easily converts an I.V. fluid pumping system to a gravity flow I.V. system. Additionally, it is an object of the present invention to provide an inexpensive, easily manufactured and simple to operate device which improves the flexibility of an I.V. administration system.